fix CI and be more strict also on the operator() call

Scripts/developer_scripts/test_merge_of_branch

@@ -220,9 +220,9 @@ git_dir=`pwd`
 tmp_dir=`mktemp -d`
 cd $tmp_dir
 echo $tmp_dir
-echo "#include <CGAL/Named_function_parameters.h>\nstruct A{};\nint main(){" > main.cpp
+echo "#include <CGAL/Named_function_parameters.h>\nstruct A{};\nint main(){\nA a;\n" > main.cpp
 for i in `echo $nps`; do
-  echo "  CGAL::parameters::${i}(A()).${i}(A());" >> main.cpp
+  echo "  CGAL::parameters::${i}(a).${i}(a);" >> main.cpp
 done
 echo "}" >> main.cpp
 if ! g++ -DCGAL_NO_STATIC_ASSERTION_TESTS -I$git_dir/STL_Extension/include -I$git_dir/Stream_support/include -I$git_dir/Installation/include main.cpp; then